The present invention relates to door assemblies for vehicles and, in particular, it concerns a vehicle door assembly which provides both hinged and sliding functions.
Known vehicle door assemblies may be broadly classified according to their opening movement into "hinged doors" and "sliding doors". Hinged doors open by rotation of the entire door about the axis of a hinge attached to the vehicle body, while sliding doors move in a sideways sliding action, typically parallel to the vehicle exterior, to a position displaced from the door surround.
Each of these door assembly types has its own particular advantages and disadvantages. Hinged doors are simple to implement, and are convenient for the user to open and close. As a result, hinged doors have generally been preferred for cars and vans intended primarily for carrying passengers. Nevertheless, hinged doors are far from ideal. Firstly, they require an open space next to the vehicle for opening, becoming difficult to use when insufficient space is available. This has ecological ramifications, requiring wasteful spacing between vehicles for parking. Furthermore, the greater the size of the door opening required, the more space is required to allow the door to swing to its open positions. Finally, even when fully opened, the outwardly projecting door limits access to the opening for loading and unloading the vehicle.
Sliding doors, on the other hand, avoid problems of wasted space and provide maximal access to the opening for loading and unloading. Implementation of sliding doors in vehicles, however, is somewhat complicated. Specifically, aerodynamic and aesthetic considerations generally require that the door, when closed, present a surface substantially continuous with the outer surface of the vehicle. At the same time, for the door to slide, it must stand clear of the door surround. These conflicting considerations are reconciled by various complicated swing-and-slide mechanisms in which the rear edge of the door performs an initial arcuate motion at the beginning of the sliding motion. Examples of such mechanisms may be found in U.S. Pat. Nos. 4,068,407 to Podolan et al. and 4,110,934 to Zens.
Swing-and-slide mechanisms such as those mentioned require complicated lock mechanisms to lock both types of movement, resulting in relatively high costs. Additionally, closing of the door is typically effected by "slamming" the door with sufficient momentum to carry the door through the arcuate motion into a locked state, resulting in a potential safety hazard to fingers. Finally, sliding door assemblies typically require a track located along an adjacent part of the outside of the vehicle. The presence of this track is aesthetically undesirable and limits the positioning of sliding doors to parts of a vehicle which have sufficient flat surfaces adjacent to the door opening.
In the field of doors for buildings, it has been known for many years to provide sliding doors which can also be opened in a hinged motion. An example of such a door assembly can be found in U.S. Pat. No. 2,565,383 to Linchaugh. Such door assemblies have not, however, been used in vehicles, nor would they appear suitable for vehicular applications.
There is therefore a need for a sliding door assembly for vehicles which would combine the advantages of hinged and sliding doors. It would also be highly advantageous to provide a vehicle door assembly which can be opened in either a hinged or a sliding movement as required.